Wireless communication networks (as for example 2G, 3G, 4G, 5G, LTE networks, WIFI networks) are rolled out in many parts of the developed world and the traffic they manage is continuously increasing. Said networks are radio network that provides coverage over different land areas called cells each served by means of at least one fixed-location transceiver (including an antenna for transmission/reception) known as base station or cell site (this type of networks are also called cellular communications networks). Usually, to avoid interference and to provide guaranteed bandwidth within each cell, each cell uses a different set of frequencies from neighboring cells. When joined together, these cells provide radio coverage over a wide geographic area.
Each cell (also called antenna cell) is assumed to give coverage to a certain area, which can be represented by a coverage polygon associated to that cell. But the same area (or part of it) can also be covered by other cells in order to give redundancy and make the network more robust to cell failures. So, the network coverage can be globally represented by a huge amount of overlapping coverage polygons (each one associated to one cell).
The radio access network is the most complex and expensive part of a mobile network, so it has to be carefully designed (number of cells, location of each cell, TX/RX capacity of each cell . . . ). Operators use radio network planning tools for this purpose. However, the traffic managed by each cell of the network is not fixed but changes significantly in short period of times (for example, due to the appearance of new services or to the celebration of a massive event or because a new building is built in a certain area or for many other reasons). So it is not enough to have a good design at the beginning of the deployment of the network but said design must be optimized every certain (short) period of time to assure that the quality of service offered to the user is maintained. For example, some new cells must be added in certain zones where the traffic has increased, some existing cells must be moved or removed, the capacity of the cells must be increased o decreased, some working parameters of the cells must be changed . . . . And, of course, said optimization must be done maintaining the quality of service and minimizing the radio resources used (as they are very expensive for the network operator).
In order to perform said radio access network optimization it is fundamental to have updated information about the network activity in the coverage area. The network activity can be defined as the usage of the network resources (for example in a certain zone or in a certain cell). This network activity depend on many different parameters and it can be therefore measured directly or indirectly in many different ways, for example, the traffic load and/or the number of calls and/or the bandwidth occupied and/or number of SMSs or number of users using a certain communications service . . . .
The normal operation of cellular networks registers the activity that is being processed by each individual cell at a certain time. But it is not obvious to have a mapping from the cell activity to the terrain. Though the antenna is known to be geographically located in a certain place, the activity processed by that antenna really can take place at any point inside its coverage area. That is, the cell does not give further information about how said activity is distributed inside its coverage area.
And furthermore, the coverage areas of the cells are overlapped. Actually many of the areas inside the network coverage area (especially in high traffic zones as cities) are covered by more than one cell, making even more difficult to exactly know the network activity in a certain area inside the network coverage area.
Having a set of cells that produces overlapping coverage over a geographic area makes difficult to have a clear view of which resulting network activity takes place in a certain portion of the land area. It is much easier to represent and understand the network activity if it is assigned to non-overlapping portions covering the whole wide area of interest. For example, the wide area of interest can be segmented into tiles using a grid. However, simplifications that force that no overlapping exists between antenna cell coverage areas (as with a pure Voronoi tessellation) are unrealistic. So, a method is needed to obtain the coverage in non-overlapping tiles from antenna cells whose coverage may overlap as it usually occurs.
There are some prior art proposals which disclose techniques to map somehow the cell activity to the terrain.
For example, U.S. Pat. No. 8,437,765B2 shows a method that involves identifying the mobile devices within a geographical area associated with a carrier network. The values to the small cells are assigned based on the network statistics. The geographical area is divided into the cells. A grid map is created for the geographical area. The grid map is divided into grids based on a coverage area associated with one of the small cells. The total values for the grids are calculated based on the assigned values. The grids are selected to place the small cells based on the total values.
U.S. Pat. No. 6,853,845B2 shows a method and system to determine an enhanced cell coverage locating a mobile terminal in a cellular mobile communication system. The geographical area is divided into pixels. The nearest antenna is found for every pixel and all pixels assigned to an antenna constitute the antenna cell. A rectangular area covering this area is constructed, and the smallest circle that covers it is the enhanced cell of the antenna.
But none of the prior art solutions solves successfully the above stated problems of mapping the network activity in non-overlapping areas. Furthermore, current solutions do not take into account the following facts:
The terrain has different features (lakes, buildings, roads . . . ) that influence how much network activity can be assigned to a particular grid tile, depending on how many people use to be populating that grid. Two different tiles, in spite of having the same area and being covered by the same set of cells, can receive different quantities of network activity depending of its land use information.
The coverage associated to each network cell is known to vary depending on the distance from the antenna. So it is unsatisfactory to consider a uniform coverage inside a single coverage polygon associated to one cell.
Hence, it is necessary a technique that assigns as exactly and efficiently as possible the network activity to land areas (e.g. in a map) to allow an optimization of the radio access design and management taking into account as much as possible the real and updated distribution of the network activity in the coverage area. The proposed embodiments of the invention stated below will provide said mechanisms, overcoming at least some of the drawbacks of the prior art solutions.